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Inguinal lymph nodes

The inguinal lymph nodes are a group of lymph nodes located in the groin region. They play a vital role in the lymphatic drainage of the lower limb, external genitalia, perineum, and lower abdominal wall. They are clinically important because enlargement may indicate infection, malignancy, or systemic disease. In surgery and oncology, they are key landmarks for staging and treatment planning.

Synonyms

  • Groin lymph nodes

  • Superficial and deep inguinal nodes

  • Inguinal nodal group

Location and Groups

  • Superficial inguinal lymph nodes:

    • Found in the superficial fascia of the groin, arranged parallel and inferior to the inguinal ligament

    • Subdivided into horizontal and vertical groups

  • Deep inguinal lymph nodes:

    • Located deep to the fascia lata, along the femoral vein within the femoral canal

    • Include the node of Cloquet (Rosenmüller’s node), the most superior deep inguinal node at the femoral canal

Relations

  • Anteriorly: Skin and superficial fascia of the groin

  • Posteriorly: Iliopsoas and pectineus muscles

  • Medially: Pubic tubercle and symphysis

  • Laterally: Anterior superior iliac spine (ASIS) and femoral vessels

Function

  • Drain lymph from the skin and subcutaneous tissues of the lower limb (except posterior calf and heel)

  • Drain lymph from the lower abdominal wall, perineum, and external genitalia (excluding testes)

  • Act as filtration centers, trapping pathogens, tumor cells, and debris

  • Play an immune surveillance role by housing lymphocytes and macrophages

Clinical Significance

  • Enlargement may be due to infection, inflammation, or malignancy (e.g., lymphoma, metastatic cancer from lower limb, genitalia, anus, or abdominal wall)

  • Palpable during physical examination of groin masses

  • Target for biopsy or sentinel node mapping in oncology (e.g., melanoma, vulvar cancer, penile cancer)

  • Involved in staging for pelvic and lower limb cancers

  • May mimic or be mimicked by femoral hernia or vascular lesions on imaging

MRI Appearance

T1-weighted images:

  • Lymph nodes appear as oval or round structures with low-to-intermediate signal intensity

  • Fatty hilum, if present, appears with high signal intensity

T2-weighted images:

  • Nodes typically show intermediate to high signal intensity relative to muscle

  • Reactive or inflamed nodes may appear more hyperintense

STIR (Short Tau Inversion Recovery):

  • Normal nodes show intermediate-to-high signal

  • Pathological nodes (inflammatory or malignant) appear with bright hyperintensity and loss of fatty hilum

T1 Fat-Sat Post-Contrast:

  • Normal nodes enhance mildly and uniformly

  • Malignant nodes often show heterogeneous or irregular enhancement

  • Abscessed nodes demonstrate rim enhancement with central non-enhancing necrosis

CT Appearance

Non-Contrast CT:

  • Nodes appear as soft tissue density structures in the groin

  • Fatty hilum, if present, appears as central low density

  • Enlarged nodes may lose hilum and appear as solid soft tissue masses

Post-Contrast CT:

  • Normal nodes enhance mildly and homogeneously

  • Reactive nodes may show uniform but more prominent enhancement

  • Malignant or necrotic nodes often show heterogeneous enhancement or rim enhancement with central low attenuation

MRI image

Inguinal lymph nodes MRI axial anatomy image-img-00000-00000

MRI image

Inguinal lymph nodes MRI CORONAL anatomy image-img-00000-00000

CT image

Inguinal lymph nodes CT axial anatomy image-img-00000-00000

CT image

Inguinal lymph nodes CT coronal anatomy image-img-00000-00000